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A temperature at or below freezing is not absolutely necessary to get ground frost or hoar frost; they can form even if air temperature is marginally above freezing point if the sky is clear. This is because the ground loses heat due to radiation. It radiates its heat to the sky/space. The amount of
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There exist some scales defining several degrees of frost severity (from "slight" to "very severe") but they depend on location thus the usual temperatures occurring in winter. The primary symptom of frost weather is that water freezes. If the temperature is low for sufficiently long time, freezing
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radiation). On a clear night the ground can become colder than the air because it radiates its heat to the sky, and ground frost can form. On the other hand, a temperature below the freezing point of water does not mean that hoar frost must occur.
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The
English word "frost" has 2 base meanings that are related to each other but nevertheless sufficiently different:
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proportional to the difference of the fourth power of the temperatures between the two objects
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will occur with some delay in lakes, rivers, and the sea. It can occur even in
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129:"hoar frost" and "ground frost" for deposit of ice on cold surfaces (see
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204:. Geneva: Secretariat of the World Meteorological Organization. 1992.
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126:"freezing" for temperature of air below the freezing point of water
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temperature of air below the freezing point of water (ca 273
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Relation between freezing and hoar frost or ground frost
30:"Air frost" redirects here. Not to be confused with
27:Air temperature below the freezing point of water
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122:avoids the word "frost" alone and uses
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202:International Meteorological Vocabulary
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99:in the picture shows -17 °C (1.4 °F).
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180:(deposit of ice on cold surfaces)
114:deposit of ice on cold surfaces
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226:Snow or ice weather phenomena
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170:(permanently frozen ground)
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149:cosmic microwave background
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91:In the southern part of
231:Atmospheric temperature
143:heat that radiates is
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39:Frost (disambiguation)
164:(the physical aspect)
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77:water supply networks
37:For other uses, see
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18:Frost (temperature)
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131:Hoar frost
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162:Freezing
156:See also
45:Freezing
93:Finland
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174:Frost
49:frost
178:Rime
176:and
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109:K
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